Walls systems having a masonry exterior are typically constructed of at least one vertical layer of masonry and at least a second vertical layer of a material forming a back-up system. The back-up system may be constructed of lumber or of a concrete masonry unit. The brick and back-up system are typically bonded together by horizontal metallic ties spaced 16 inches in a vertical plane. A space is often provided in such wall systems (e.g., cavity wall systems) between the brick and back-up system for moisture drainage. Insulation may also be placed in the space to improve the energy efficiency of masonry buildings.
Masonry offers great durability and appeal. Masonry walls, however, tend to be permeable, allowing water to pass through the wall under certain conditions, such as storms associated with high winds. To solve the water leakage problem, recent construction trends have been towards a masonry wall system where the brick is intentionally separated from the back-up by a small vertical space of from 1-4 inches. When insulation is placed in the space, an effort is made to maintain at least one inch of space between the brick and insulation for drainage.
Masonry walls constructed with a back-up system and intervening drainage space are relatively effective and durable when guidelines are followed and drainage space is maintained. Problems often arise in construction, however, in maintaining an unobstructed space between the brick and associated back-up system. During construction, mortar often falls into the sometimes narrowed drainage space between the brick and back-up or between the brick and insulation, blocking the flow of water out of the wall interior.
In masonry construction using brick exteriors, it is critical to provide proper drainage in the form of a clear cavity within the wall system to prevent water related problems. A proper drainage path allows penetrating water to flow unobstructed to areas of the wall which facilitate drainage back to the exterior.
Normally the 1 to 2 inch air space provided between the brick and back-up system is adequate to provide drainage. However, in addition to mortar entering the air space during the process of brick laying, mortar extruded during the brick-laying process from the outer brick wythe also accumulates in the air space creating blockages, either falling into the air space or simply extending into and blocking the air space. Environmental debris may also fall, or blow, into the air space. Obstructions from these or other sources, either singly or together, may operate to substantially block the flow of water out of portions of the air space.
When blockage of water occurs, freezing of accumulated water inside the wall may cause damage to the wall system. In masonry construction using brick exteriors, for example, it is especially important to avoid water saturation which upon freezing and thawing may lead to cracking, crazing, spalling and disintegration of masonry structures. Furthermore, penetrating water can cause efflorescence to appear on exterior surfaces or water can be transferred to the interior of the building causing: metal supports to corrode, insulation to lose its effectiveness, interior finishes to deteriorate. Because of the importance of masonry structures in general, a need exists for a better method of ensuring water drainage from within brick walls.